Methods and devices for performing a surgical anastomosis

ABSTRACT

A circular stapler is disclosed. The circular stapler comprises a handle assembly, an elongate body, and a cartridge assembly. The elongate body extends from the handle assembly and defines a longitudinal axis. The cartridge assembly is disposed adjacent a distal end of the elongate body. The cartridge assembly includes a pusher assembly and a knife assembly. The pusher assembly is movable to cause staples to be ejected from the cartridge assembly. The knife assembly is selectively movable relative to the pusher assembly to distally translate a knife. A knife carrier of the knife assembly includes at least one latch thereon. The at least one latch is configured to contact an engagement surface of the pusher assembly in response to movement between the knife carrier and the pusher assembly. The at least one latch is prevented from distally translating beyond the engagement surface.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Continuation of U.S. patent applicationSer. No. 16/361,399, filed on Mar. 22, 2019, which is a Continuation ofU.S. patent application Ser. No. 15/690,431, filed on Aug. 30, 2017, nowU.S. Pat. No. 10,245,040, which is a Divisional of U.S. patentapplication Ser. No. 13/939,684, filed on Jul. 11, 2013, now U.S. Pat.No. 9,750,503, the entire contents of each of these applications ishereby incorporated by reference.

BACKGROUND

The present disclosure relates generally to a surgical stapling devicefor applying surgical staples to body tissue. More particularly, thepresent disclosure relates to a surgical stapling device suitable forperforming circular anastomosis and/or treatment to internal walls ofhollow tissue organs.

Anastomosis is the surgical joining of separate hollow organ sections.Typically, an anastomosis procedure follows surgery in which a diseasedor defective section of hollow tissue is removed and the remaining endsections are to be joined. Depending on the desired anastomosisprocedure, the end sections may be joined by either circular,end-to-end, or side-to-side organ reconstruction methods.

In a circular anastomosis procedure, the two ends of the organ sectionsare joined by means of a stapling instrument which drives a circulararray of staples through the end section of each organ section andsimultaneously cores any tissue interior of the driven circular array ofstaples to free the tubular passage. Examples of instruments forperforming circular anastomosis of hollow organs are described in U.S.Pat. Nos. 6,053,390, 5,588,579, 5,119,983, 5,005,749, 4,646,745,4,576,167, and 4,473,077, each of which is incorporated herein in itsentirety by reference. Typically, these instruments include an elongatedshaft having a handle portion at a proximal end to actuate theinstrument and a staple holding component disposed at a distal end. Ananvil assembly including an anvil rod with attached anvil head ismounted to the distal end of the instrument adjacent the staple holdingcomponent. Opposed end portions of tissue of the hollow organ(s) to bestapled are clamped between the anvil head and the staple holdingcomponent. The clamped tissue is stapled by driving one or more staplesfrom the staple holding component so that the ends of the staples passthrough the tissue and are deformed by the anvil head. An annular knifeis advanced to core tissue within the hollow organ to free a tubularpassage within the organ. Generally, both the actuation of the stapleforming mechanism and the advancement of the knife occur at the sametime, i.e., simultaneously.

Besides anastomosis of hollow organs, surgical stapling devices forperforming circular anastomosis have been used to treat internalhemorrhoids in the rectum. Typically, during use of a circular staplingdevice for hemorrhoid treatment, the anvil head and the staple holdingcomponent of the surgical stapling device are inserted through the anusand into the rectum with the anvil head and the staple holding componentin an open or unapproximated position. Thereafter, a pursestring sutureis used to pull the internal hemorrhoidal tissue towards the anvil rod.Next, the anvil head and the staple holding component are approximatedto clamp the hemorrhoid tissue between the anvil head and the stapleholding component. The stapling device is fired to remove thehemorrhoidal tissue and staple the cut tissue.

SUMMARY

The present disclosure relates to a circular stapler comprising a handleassembly, an elongate body, and a cartridge assembly. The elongate bodyextends from the handle assembly and defines a longitudinal axis. Thecartridge assembly is disposed adjacent a distal end of the elongatebody. The cartridge assembly includes a pusher assembly and a knifeassembly. The pusher assembly is movable to cause staples to be ejectedfrom the cartridge assembly. The knife assembly is selectively movablerelative to the pusher assembly to distally translate a knife. A knifecarrier of the knife assembly includes at least one latch thereon. Theat least one latch is configured to contact an engagement surface of thepusher assembly in response to movement between the knife carrier andthe pusher assembly. The at least one latch is prevented from distallytranslating beyond the engagement surface.

In disclosed embodiments, the at least one latch of the knife carrier isincluded on a proximal end of a flexible arm, and the flexible arm isconfigured to flex toward the longitudinal axis. The knife carrier isconfigured to be assembled with the pusher assembly by moving the knifecarrier in a distal-to-proximal direction through a passage extendingthrough the pusher assembly.

In disclosed embodiments, a proximal portion of knife carrier includesan annular groove. The annular groove is configured to engage a drivemember. The annular groove is positioned farther proximally than anentirety of the at least one arm and the at least one latch. A proximalportion of the at least one latch includes a ramped surface, and adistal portion of the at least one latch includes a surface that issubstantially perpendicular to the longitudinal axis.

The present disclosure also relates to a circular stapler comprising ahandle assembly, an elongate body extending from the handle assembly anddefining a longitudinal axis, a drive member, and a cartridge assembly.The drive member is configured for longitudinal translation in responseto actuation of handle assembly, and includes a recess disposed adjacenta distal portion thereof. The cartridge assembly is disposed adjacent adistal end of the elongate body, and includes a pusher assembly. Thepusher assembly is configured to mechanically engage a portion of thedrive member and is longitudinally translatable to cause staples to beejected from the cartridge assembly. The pusher assembly includes atleast one finger with the at least one finger including a tab. The atleast one tab is configured to engage the recess of the drive member inresponse to relative approximation between the drive member and thepusher assembly.

In disclosed embodiments, a distal wall of the at least one tab forms anangle α1 with respect to the longitudinal axis, and wherein α1 isbetween about 70° and about 80°. Here, it is disclosed that a distalwall of the recess forms an angle α2 with respect to the longitudinalaxis, and wherein α2 is between about 70° and about 80°. It is furtherenvisioned that α1 is between about 75° and about 78°.

In disclosed embodiments, the at least one finger is configured to flextoward the longitudinal axis to facilitate engagement between the drivemember and the pusher assembly.

In disclosed embodiments, a height of the at least one tab in adirection substantially perpendicular to the longitudinal axis isbetween about 0.010 inches and about 0.020 inches. It is envisioned thatthe height of the at least one tab is approximately equal to 0.015inches. It is further disclosed that a depth of the recess portion in adirection substantially perpendicular to the longitudinal axis isbetween about 0.010 inches and about 0.020 inches.

In disclosed embodiments, at least a portion of the pusher assemblycomprises glass-filled polycarbonate. The percentage of glass in theglass-filled polycarbonate of the pusher assembly is between about 20%and about 40%.

In disclosed embodiments, the circular stapler further comprises a knifeassembly which is selectively movable relative to the pusher assembly todistally translate a knife.

In disclosed embodiments, the handle assembly is configured to receivepower from a power source. The circular stapler comprises acommunication chip disposed in mechanical cooperation with the cartridgeassembly. The communication chip is configured to communicateinformation to and from other portions of the circular stapler.

The present disclosure also relates to an anvil assembly for use with acircular stapler. The anvil assembly comprises an anvil head and acutting ring. The anvil head includes a plurality of staple-deformingpockets and an annular cavity. The anvil head includes a groove disposedalong an inner annular surface thereof. The cutting ring is configuredfor reception at least partially within the annular cavity, and includesat least one tab extending radially outwardly from an outer wallthereof. The at least one tab is configured to engage the groove of theanvil head to help maintain at least a portion of the cutting ring atleast partially within the cavity.

In disclosed embodiments, the cutting ring includes an outer ring, aninner ring, an annular knife channel disposed between the outer ring andthe inner ring, and a severable portion disposed proximally-adjacent theknife channel. The severable portion is configured to be cut by a knifeduring typical use of the circular stapler.

The at least one tab includes a proximal surface and a distal surface.The proximal surface of the at least one tab is substantiallyperpendicular to an annular wall of the cutting ring, and the distalsurface of the at least one tab is disposed at an angle with respect tothe annular wall of the cutting ring and with respect to the proximalsurface of the at least one tab. Here, it is disclosed that the cuttingring is configured to be inserted into the annular cavity of the anvilhead in a proximal-to-distal direction such that the distal surface ofthe at least one tab contacts a portion of the anvil head and causes thecutting ring to deflect radially inward to allow the at least one tab toextend distally beyond a lip formed by a proximal surface of the groove.It is further disclosed that the proximal surface of the at least onetab is configured to engage the lip of the groove.

The cutting ring may comprise polyethylene.

In disclosed embodiments, the at least one tab is configured to engagethe groove of the anvil head to help maintain at least a portion of thecutting ring at least partially within the cavity after a knife of thecircular stapler has been advanced, and after a portion of the cuttingring as been severed by the knife.

The present disclosure contemplates a shell assembly for use with acircular stapler. The shell assembly comprises a housing and a staplecartridge. The housing includes an aperture defining a proximal wall anda distal wall, the defines a longitudinal axis extending therethrough.The staple cartridge is configured to house a plurality of staples atleast partially therein, and includes at least one tab configured tomechanically engage the distal wall of the aperture. The at least onetab is configured to flex toward the longitudinal axis to facilitateassembly between the housing and the staple cartridge.

In disclosed embodiments, a proximal surface of the at least one tab isdisposed at an angle with respect to the longitudinal axis.

In disclosed embodiments, a distal surface of the at least one tabincludes a first surface that is substantially perpendicular to thelongitudinal axis. Here, it is disclosed that the distal surface of theat least one tab includes a second surface that is disposed at an anglewith respect to the first surface and with respect to the longitudinalaxis. It is further disclosed that the first surface is disposedradially outward of the second surface. It is further disclosed that aradially inward-most point of the distal surface is the proximal-mostpoint of the distal surface. Additionally, it is disclosed that thedistal wall of the aperture includes a first surface that issubstantially perpendicular to the longitudinal axis, and a secondsurface that is disposed at an angle with respect to the first surfaceand with respect to the longitudinal axis.

In disclosed embodiments, the shell assembly further comprises acylindrical sleeve positionable adjacent a distal portion of thehousing. The sleeve is configured to cover the aperture of the housingand the at least one tab of the staple cartridge. Here, it is disclosedthat at least a portion of the sleeve comprises plastic.

The present disclosure also relates to a shell assembly kit for use witha circular stapler. The shell assembly kit comprises a first staplecartridge, a second staple cartridge, a first anvil assembly and asecond anvil assembly. The first staple cartridge is configured to housetwo rows of staples, and includes a first trocar disposed in mechanicalcooperation therewith. The second staple cartridge is configured tohouse three rows of staples, and includes a second trocar disposed inmechanical cooperation therewith. The first anvil assembly includes tworows of staple deforming pockets, and a first retention rod configuredto mechanically engage the first trocar. The second anvil assemblyincludes three rows of staple deforming pockets, and includes a secondretention rod configured to mechanically engage the second trocar. Thefirst trocar is physically prevented from properly engaging the secondretention rod, and the second trocar is physically prevented fromproperly engaging the first retention rod.

In disclosed embodiments, the first trocar includes at least oneindicator that is perceptible by a user when the first trocar isimproperly engaged with the second retention rod. The at least oneindicator is not perceptible by a user when the first trocar is properlyengaged with the first retention rod.

In disclosed embodiments, the first retention rod includes a recess thatis configured to engage a lip of the first trocar, and the secondretention rod includes a recess that is configured to engage a lip ofthe second trocar. Here, it is disclosed that the first retention rodincludes a larger diameter than a corresponding diameter of the secondretention rod. It is further disclosed that a distance between therecess and a proximal lip of the first retention rod is less than adistance between the recess and a proximal lip of the second retentionrod.

In disclosed embodiments, a tissue-contacting portion of the firstretention rod is tapered along its entire length. Here, it is disclosedthat an anvil head of the first anvil assembly is tiltable with respectto the first retention rod.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of a surgical stapling instrument are disclosed herein withreference to the drawings, wherein:

FIG. 1 is a perspective view of a surgical stapling instrument accordingto an embodiment of the present disclosure;

FIG. 2 is an enlarged perspective view of a cartridge assembly of thesurgical stapling instrument of FIG. 1;

FIG. 3 is an exploded perspective view of the cartridge assembly of FIG.2;

FIG. 4 is a perspective view of a shell assembly in an approximatedposition, and includes the cartridge assembly of FIGS. 2 and 3;

FIG. 5 is an enlarged view of the area of detail indicated in FIG. 4;

FIG. 6 is a perspective view of a staple guide separated from an outerhousing of the cartridge assembly;

FIG. 7 is a cut-away view of the area of detail indicated in FIG. 5;

FIG. 8 is an enlarged view of the area of detail indicated in FIG. 7;

FIG. 9 is a perspective view of a sleeve configured for use with theshell assembly of the present disclosure;

FIG. 10 is a perspective view of the sleeve of FIG. 9 positioned on theshell assembly;

FIG. 11 is a perspective view of a knife carrier engaged with a pusheradapter of the cartridge assembly of the present disclosure;

FIG. 12 is an enlarged view of the area of detail indicated in FIG. 11;

FIG. 13 is a perspective view of the knife carrier of FIG. 11;

FIG. 14 is a perspective view of the pusher adapter of FIG. 11;

FIG. 15 is a cut-away perspective view of the pusher adapter taken alongline 15-15 in FIG. 14;

FIG. 16 is a cross-section view of the knife carrier engaged with thepusher adapter of FIG. 11;

FIG. 17 is enlarged view of the area of detail indicated in FIG. 16;

FIG. 18 is a cross-sectional view of the shell assembly illustrating thepusher adapter of FIG. 11 in an advanced position;

FIG. 19 is a cross-sectional view of the shell assembly illustrating theknife carrier of FIG. 11 in an advanced position;

FIG. 20 is an enlarged view of the area of detail indicated in FIG. 19;

FIG. 21 is a cross-sectional view of the shell assembly illustrating theknife carrier of FIG. 11 in a retracted position;

FIG. 22 is a perspective view of a portion of an anvil assemblyincluding a cutting ring in accordance with embodiments of the presentdisclosure;

FIG. 23 is a perspective view of the cutting ring of FIG. 22;

FIG. 24 is a perspective view of an anvil head of the anvil assembly ofFIG. 22;

FIG. 25 is a cut-away perspective view of a portion of the anvil head ofFIG. 24;

FIG. 26 is a cut-away perspective view of a portion of the anvilassembly of FIG. 22 engaged with the shell assembly of the presentdisclosure, and illustrating a knife in a proximal position;

FIG. 27 is a cut-away perspective view of the portions of the anvilassembly and shell assembly of FIG. 26, and illustrating the knife in anadvanced position;

FIG. 28 is a perspective view of an anvil assembly in accordance with anembodiment of the present disclosure;

FIG. 29 is a side view of the anvil assembly of FIG. 28 shown with theanvil head within tissue;

FIG. 30 is a side view of the anvil assembly of FIGS. 28 and 29 shownwith the anvil head in a titled position and within tissue;

FIG. 31 is a perspective view of a first trocar in accordance with thepresent disclosure;

FIG. 32 is a longitudinal cross-sectional view of the first trocar ofFIG. 31 engaged with a first retention rod;

FIG. 32A is a longitudinal cross-sectional view of a second trocarengaged with a second retention rod in accordance with the presentdisclosure;

FIG. 33 is a longitudinal cross-sectional view the second trocarpartially engaged with the first retention rod;

FIG. 34 is a longitudinal cross-sectional view the first trocarpartially engaged with the second retention rod;

FIG. 35 is a perspective, assembly view of a portion of a drive memberand a pusher adapter in accordance with embodiments of the presentdisclosure;

FIGS. 36-38 are longitudinal cross-sectional views of the portion of thedrive member and the pusher adapter of FIG. 35 illustrated in variousstages of engagement;

FIG. 39 is a perspective view of the portion of the drive member and thepusher adapter of FIG. 35 in an engaged position;

FIG. 40 is a perspective view of communication chip assembly inaccordance with embodiments of the present disclosure; and

FIG. 41 is a perspective, cut-away view of the communication chipassembly of FIG. 40 positioned within a shell assembly.

DETAILED DESCRIPTION

Embodiments of the presently disclosed surgical stapling instrument willnow be described in detail with reference to the drawings wherein likenumerals designate identical or corresponding elements in each of theseveral views. As is common in the art, the term “proximal” refers tothat part or component closer to the user or operator, i.e. surgeon orphysician, while the term “distal” refers to that part or componentfarther away from the user.

FIG. 1 illustrates an embodiment of a surgical stapling instrumentaccording to the present disclosure, referenced generally as circularstapler 10. Circular stapler 10 includes a handle assembly 20, anelongated body portion 30 extending distally from handle assembly 20,and a shell assembly 100 mounted adjacent a distal end of elongated bodyportion 30. Handle assembly 20 includes a fixed handle 22 and a moveablehandle or trigger 24. Handle assembly 20 also includes an approximationknob 26 for moving an anvil assembly 105 relative to a cartridgeassembly 110 of shell assembly 100. The structure and function of handleassembly 20 will only be described herein to the extent necessary tofully disclose the operation of shell assembly 100. It is envisionedthat shell assembly 100 may be used with any actuation assembly, poweredor manual, and capable of two independent actuation strokes, forexample. Commonly-owned U.S. patent application Ser. No. 12/946,082,filed Nov. 15, 2010, now U.S. Pat. No. 8,806,73, the entire contents ofwhich being incorporated by reference herein, discloses a surgicaldevice having a powered actuator assembly including first and seconddrive members. In addition, it is envisioned that the independentactuation strokes may be completed by the same drive member completingtwo strokes or by two separate drive members.

With reference to FIG. 2, cartridge assembly 110 is shown, and isoperably mounted to a distal end of elongated body portion 30 ofcircular stapler 10 (FIG. 1). In disclosed embodiments, cartridgeassembly 110 is removably secured to elongated body portion 30 such thatcartridge assembly 110, or a portion thereof, may be replaced andcircular stapler 10 may be reused. In other embodiments, only a portionof cartridge assembly 110 is configured to be removed, and subsequentlyreplaced or reloaded. Alternatively, circular stapler 10 may beconfigured for a single use, i.e., disposable.

With reference to FIGS. 2 and 3, cartridge assembly 110 includes ahousing 120, a pusher assembly 530, a staple cartridge 150, and a knifeassembly 400. Housing 120 of cartridge assembly 110 includes an outercylindrical portion 122, an inner cylindrical body 124 and a pluralityof radially extending supports or ribs (not shown) extending between andinterconnecting inner cylindrical portion 124 and outer cylindricalportion 122. Inner cylindrical portion 124 and outer cylindrical portion122 are coaxial and define a recess 123 therebetween configured toreceive a distal portion of pusher assembly 530 and knife assembly 400.

Knife assembly 400 includes a knife carrier 420 and a circular knife440. Knife 440 is a substantially cylindrical member having a proximalend 442, a distal end 444, and defines a longitudinal opening 443therethrough. Knife 440 is sized and configured to be received throughrecess 123 of staple cartridge 150. Distal end 444 of knife 440 isconfigured for cutting tissue. Proximal end 442 of knife 440 isconfigured to be received about a distal portion 424 of knife carrier420 and includes a pair of opposed tabs 446 configured to be receivedwithin respective recesses 421 formed in distal portion 424 of knifecarrier 420.

A proximal portion 422 of knife carrier 420 defines an annular groove463 configured to accommodate snap ring 180 when snap ring 180 is ineither a first or compressed condition or in a second or expandedcondition. When circular stapler 10 is in the first or initial position,and prior to retraction of pusher adapter 532 following the first strokeof circular stapler 10, snap ring 180 is received completely withinannular groove 463 formed in knife carrier 420. Proximal portion 422 ofknife carrier 420 further defines a step 462 a formed in or adjacentannular groove 463. Step 462 a is configured to engage an inner annularportion of snap ring 180 when snap ring 180 is in the second or expandedcondition. Further, engagement of snap ring 180 with step 462 a preventsradial compression of snap ring 180 during the second or tissue cuttingstroke. Further details of snap ring 180 and its engagement with knifecarrier 420 are described in U.S. patent application Ser. No. 13/739,246filed on Jan. 11, 2013, now U.S. Pat. No. 9,351,24, the entire contentsof which being incorporated by reference herein.

With continued reference to FIGS. 2 and 3, a proximal end 122 a of outercylindrical portion 122 of housing 120 includes a plurality of tabs 125formed thereon configured to operably engage cartridge assembly 110 witha distal end of elongated body portion 30 (FIG. 1). Outer cylindricalportion 122 of housing 120 further defines a plurality of openings 129.As will be discussed in further detail below, each of the plurality ofopenings 129 is configured to engage a pair of a plurality of detents538 a, 538 b formed on a distal portion 534 of a pusher adapter 532.

With reference now to FIG. 3, pusher assembly 530 includes pusheradapter 532 and a pusher member 540. Pusher adapter 532 is asubstantially cylindrical member having a proximal portion 532 a and adistal portion 534. Proximal portion 532 a of pusher adapter 532 isconfigured for operable engagement with a drive member 800 (e.g., seethe embodiment disclosed in FIGS. 35-39). Distal portion 534 of pusheradapter 532 is configured to operably engage pusher member 540. As willbe discussed in further detail below, pusher member 540 is not securelyaffixed to pusher adapter 532, such that pusher member 540 remains in anadvanced position during the retraction of pusher adapter 532 followingthe first or stapling stroke of circular stapler 10. In this manner, theforce required to move pusher adapter 532 during the second or tissuecutting stroke of circular stapler 10 does not include the forcenecessary to move pusher member 540.

With continued reference to FIG. 3, pusher adapter 532 defines alongitudinal passage 531 extending therethrough. A distal end oflongitudinal passage 531 is sized and configured to receive knifeassembly 400 in a sliding manner. Pusher adapter 532 further defines aplurality of longitudinal slots 533 extending along a length thereof.Slots 533 correspond in size and location to the supports (not shown)formed between and interconnecting outer and inner cylindrical portions122, 124 in housing 120. Pusher adapter 532 is configured to be receivedwithin outer cylindrical portion 122 of housing 120 and about innercylindrical portion 124 of housing 120. In this manner, slots 533receive the respective supports of housing 120 such that innercylindrical portion 124 of housing 120 may be received withinlongitudinal passage 531 of pusher adapter 532. A plurality of recesses535 a are formed in a distal surface 534 a of pusher adapter 532 and areconfigured to engage tabs (not shown) formed on a proximal-facingsurface of pusher member 540 (e.g., to ensure radial alignment duringthe firing stroke). As discussed above, pusher adapter 532 includes aplurality of paired detents 538 a, 538 b configured to be selectivelyreceived within openings 129 formed in outer cylindrical portion 122 ofhousing 120.

With continued reference to FIG. 3, pusher member 540 includes aproximal portion 542 and a distal portion 544. Proximal portion 542 ofpusher member 540 defines a plurality of tabs (not shown) configured tobe selectively received within the plurality of recesses 535 a formed ondistal surface 534 a of pusher adapter 532. Distal portion 544 of pushermember 540 includes a plurality of pusher elements 546 extendingdistally therefrom and arranged in three concentric rows. Pusherelements 546 align with staples “S” received within staple cartridge 150such that advancement of pusher member 540 relative to staple cartridge150 causes ejection of staples “S” from staple cartridge 150. A notch535 formed in distal portion 534 of pusher adapter 532 is configured toreceive an outer annular portion of snap ring 180 of knife assembly 400,and a ledge 536 of pusher adapter 532 is configured to engage the outerannular portion of snap ring 180 during the second or cutting stroke ofcircular stapler 10. Additionally, tabs 536 a are configured to retainsnap ring 180 in engagement within distal portion 534 of pusher adapter532.

With reference to FIGS. 2 and 3, staple cartridge 150 is a substantiallycylindrical member configured to operably engage distal end 122 b ofouter cylindrical portion 122 of housing 120 and defines a longitudinalopening 151. Staple cartridge 150 includes a plurality of staplereceiving pockets 152 disposed about opening 151 arranged in threeconcentric rows. Staple receiving pockets 152 align with pusher elements546 formed on distal portion 544 of pusher member 540.

With reference to FIG. 4-8, the engagement between housing 120 andstaple cartridge 150 is illustrated. Housing 120 and staple cartridge150 are configured to mechanically engage each other prior to use ofcircular stapler 10 (e.g., during assembly). In this embodiment, housing120 is engagable with staple cartridge 150 via a mechanical interface.More particularly, housing 120 includes at least one aperture 200 thatis engagable with at least one tab 300 on staple cartridge 150.

Tabs 300 on staple cartridge 150 are inwardly flexible (with respect toa longitudinal axis A-A defined by elongated body portion 30) tofacilitate assembly. Tabs 300 include a ramped proximal surface 302, anda distal surface 304 (FIG. 8). It is envisioned that distal surface 304includes a substantially perpendicular surface 306 (with respect tolongitudinal axis A-A), a ramped surface 308, or a combination thereof.In the illustrated embodiment (see FIG. 8, for example), distal surface304 of tab 300 includes a perpendicular surface 306 and a ramped surface308. Ramped surface 308 is angled such that the portion closer to thelongitudinal axis A-A is disposed proximally of the portion of rampedsurface 308 that is farther from the longitudinal axis A-A. It isenvisioned that staple cartridge 150 includes any number of tabs 300.

Apertures 200 on housing 120 are dimensioned and positioned formechanical engagement with tabs 300. It is envisioned that housing 120includes any number of apertures 200. It is further envisioned that thenumber of apertures 200 is equal to or unequal to the number of tabs300. Additionally, it is disclosed that the dimensions and/ororientation of tabs 300 and apertures 200 only allow engagementtherebetween in a single radial orientation (e.g., for mistake-proofassembly). It is envisioned that a distal wall 202 of aperture 200includes a substantially perpendicular surface 204 (with respect tolongitudinal axis A-A), a ramped surface 206, or a combination thereof.In the illustrated embodiment (see FIG. 8, for example), distal wall 202of aperture 200 includes a perpendicular surface 204 and a rampedsurface 206. Ramped surface 206 is angled such that the portion closerto the longitudinal axis A-A is disposed proximally of the portion oframped surface 206 that is farther from the longitudinal axis A-A. Asshown, the orientation of distal wall 202 of aperture 200 iscomplementary to the orientation of distal surface 304 of tab 300.

It is envisioned that the complementary surfaces of distal wall 202 anddistal surface 304, including ramped surfaces 206 and 308, respectively,help provide improved retention between housing 120 and staple cartridge150. In this embodiment, a greater force (e.g., in the substantialdirection of arrow “F” in FIG. 8) would be required to disengage staplecartridge 150 from outer housing 120 with respect to an embodiment wheredistal surface 304 of tab 300 and distal wall 202 of aperture 200 do notinclude ramped surfaces 308 and 206, respectively.

In the illustrated embodiment, housing 120 also includes a plurality oflongitudinal slots 220, with one slot 220 being disposed on each side ofeach aperture 200. Slots 220 extend proximally from a distal edge 222 ofhousing 120. It is envisioned that slots 220 enable radially outwardflexing of the portion of housing 120 surrounding apertures 200 tofacilitate the mechanical engagement between housing 120 and staplecartridge 150. As can be appreciated, to mechanically engage housing 120and staple cartridge 150, the two components are approximated such thatthe portion of housing 120 surrounding apertures 200 flexes radiallyoutward to allow tabs 300 of staple cartridge 150 to enter apertures200. After tabs 300 are within respective apertures 200, the portion ofhousing 120 surrounding apertures 200 flexes radially inward toeffectively lock housing 120 and staple cartridge 150 together.

It is envisioned that the mechanical engagement between housing 120 andstaple cartridge 150 is the only type of engagement therebetween. Forexample, the mechanical engagement eliminates the need for adhesivesbetween the two components or welding the components together.

With reference to FIGS. 9 and 10, the present disclosure includes alabel (e.g., an adhesive label) or sleeve (e.g., a shrink sleeve) 350.Sleeve 350 is positionable adjacent a distal portion of housing 120 andis configured to cover apertures 200, slots 220 and tabs 300 (see FIG.5). The use of sleeve 350 helps ensure tissue does not because trappedor pinched within apertures 200, slots 220 or tabs 300, and also helpslimit radially outward movement of tabs 300 with regard to apertures 200during insertion of housing 120 into tissue, for example.

Additionally, it is envisioned that sleeve 350 can include information(e.g., indicia or a color) relating to lumen and/or staple size of thestapling instrument, for example. It is envisioned that thecircumference of sleeve 350 is equal to or larger than the circumferenceof the distal portion of housing 120. In the embodiments where sleeve350 has a larger circumference, an overlapping portion of sleeve 350will cover the longitudinal seam between sleeve 350 and housing 120. Itis envisioned that sleeve 350 is made from plastic (e.g., polyvinylchloride (PVC), polyethylene terephthalate (PET), polypropylene, etc.)or another suitable material.

With reference to FIGS. 11-21, the engagement between pusher adapter 532and knife carrier 420 is shown. With particular reference to FIGS. 12and 13, proximal portion 422 of knife carrier 420 includes a pluralityof latches 426, which are each configured to mechanically engage anengagement surface 550 (e.g., an undercut surface) of pusher adapter 532upon a predetermined amount of longitudinal translation of knife carrier420 with respect to pusher adapter 532. As can be appreciated, theengagement between latches 426 and engagement surfaces 550 prevent orsubstantially prevent portions of knife carrier 420 from translatingdistally beyond portions of pusher adapter 532.

More particularly, latches 426 of knife carrier 420 are disposed at aproximal end of flexible arms 428. Arms 428 are configured to deflecttoward a radial center of knife carrier 420 to facilitateengagement/assembly between knife carrier 420 and pusher adapter 532.Further, to assemble knife carrier 420 and pusher adapter 532, knifecarrier 420 is inserted in a proximal direction through a distal opening560 of pusher adapter 532 until a ramped surface 430 of latches 426contacts an angled surface 562 of an interior wall of pusher adapter532. The contact between ramped surfaces 430 and angled surface 562, incombination with the proximal movement of knife carrier 420 with respectto pusher adapter 532, causes arms 428 to deflect radially inwardly,which allows a distal wall 426 a of latches 426 to move proximallybeyond engagement surfaces 550 of pusher adapter 532. Once in thisposition, arms 428 deflect radially outwardly (e.g., towards theirbiased position) such that distal walls 426 a of latches 426 arephysically prevented by engagement surfaces 550 of pusher adapter 532from longitudinally translating distally therepast (see FIGS. 16 and17). It is further envisioned that distal walls 426 a of latches 426include a ramped surface (e.g., the proximal portion of the rampedsurface being closest to the radial center of knife carrier 420), andthat engagement surfaces 550 of pusher adapter 532 include acomplementary surface.

Referring now to FIGS. 16-21, the relative movement between pusheradapter 532, knife carrier 420 and housing 120 is depicted. FIG. 16illustrates pusher adapter 532 and knife carrier 420 in a retractedposition. As shown in FIG. 17 (which is an enlarged view of a portion ofFIG. 16), the orientation of latches 426 and engagement surfaces 550limit the amount of distal travel of knife carrier 420 with respect topusher adapter 532. As can be appreciated, this orientation prevents auser from cutting tissue prior to the tissue being stapled. FIG. 18illustrates pusher adapter 532 in an advanced position, and knifecarrier 420 in its retracted position (e.g., in response to a firstactuation stroke to staple tissue). FIG. 19 illustrates pusher adapter532 in its advanced position, and knife carrier 420 in an advancedposition (e.g., in response to a second actuation stroke to cut tissue).As shown in FIG. 20 (which is an enlarged view of a portion of FIG. 19),the engagement between latches 426 and engagement surfaces 550 preventadditional distal travel of knife carrier 420 with respect to pusheradapter 532. FIG. 21 illustrates pusher adapter 532 in its advancedposition, and knife carrier 420 in its retracted position (e.g., aftertissue has been cut). As can be appreciated, that fact that pusheradapter 532 remains in its advanced position in this embodiment helpsprevent inadvertent contact between knife 440 and a user of circularstapler 10, and between knife 440 and a patient.

In addition to the embodiment disclosed herein where a proximal portion422 of knife carrier 420 is configured to engage snap ring 180, anotherembodiment is disclosed where proximal portion 422 of knife carrier 420is configured to mechanically engage a drive member or sleeve 450 whenknife carrier 420 mechanically engages pusher adapter 532. Moreparticularly, in this embodiment, annular groove 463 of proximal portion422 of knife carrier 420 is included on plurality of legs 460 (FIG. 13),with each leg 460 including a portion of annular groove 463 which isconfigured to engage a lip 452 of drive sleeve 450 (FIGS. 16, 18, 19 and21). Further, legs 460 are configured to deflect radially inwardly,which allows proximal portion 422 of knife carrier 420 to belongitudinally translated proximally beyond lip 452 of drive sleeve 450,thus effectively coupling knife carrier 420 with drive sleeve 450 (seeFIGS. 16, 18, 19 and 21, for example). As can be appreciated, in thisembodiment, longitudinal translation of drive sleeve 450 (e.g., via asecond actuation stroke of handle 24) causes a correspondinglongitudinal translation of knife carrier 420.

With reference to FIGS. 22-27, further details of anvil assembly 105 areillustrated in accordance with embodiments of the present disclosure.Anvil assembly 105 is longitudinally movable with respect to cartridgeassembly 110, and includes a retention rod 108, which selectivelyconnects anvil assembly 105 with the remainder of surgical stapler 10.Anvil assembly 105 includes an anvil head 600 and a cutting ring 620.Anvil head 600 includes a plurality of staple-deforming pockets 602formed directly therein (i.e., without the inclusion of a traditionalanvil plate). Pockets 602 are configured to receive legs of the staplesejected from staple cartridge 110 and to deform the legs into anappropriate shape. In the illustrated embodiment, pockets 602 aredisposed in three rows and annularly extend along a tissue-contactingsurface 604 of anvil head 600. Anvil assembly 105 also includes anattachment member 606 extending proximally from anvil head 600.Attachment member 606 is configured to pivotably engage retention rod108. An annular cavity 608 is defined by anvil head 606 and is disposedaround (e.g., surrounding) attachment member 606 (FIGS. 24 and 25). Itis envisioned that the entirety of anvil head 606 is monolithicallyformed and/or is made of the same material.

Cutting ring 620 is configured for positioning within annular cavity 608of anvil head 600. More particularly, cutting ring 620 includes an outerring 622, an inner ring 624, an annular knife channel 626 disposedbetween outer ring 622 and inner ring 624, and a severable portion 628disposed proximally-adjacent knife channel 626. Severable portion 628 isconfigured to be cut by knife 440 (see FIGS. 26 and 27) during thecutting stroke of circular instrument 10.

Cutting ring 620 also includes a plurality of tabs 630 disposed aroundits outer annular edge 622. Tabs 630 are configured to mechanicallyengage a groove 610 disposed around an inner annular surface 612 ofanvil head 600. Any number of tabs 630 (including a single tab 630 thatextends along the entire surface 612) may be included on cutting ring620. More particularly, each tab 630 includes a proximal surface 632that is substantially perpendicular to annular edge 629, and a distalsurface 634 that is angled with respect to annular edge 629 and withrespect to proximal surface 632.

Distal surface 634 of tab 630 is configured to facilitate assemblybetween cutting ring 620 and anvil head 600. That is, during assembly,cutting ring 620 is inserted into annular cavity 608 in aproximal-to-distal direction such that distal surface 634 contacts aportion of anvil head 600 and causes cutting ring 620 to deflectradially inwardly to allow tabs 630 to extend distally beyond a lip 611formed by a proximal surface of groove 610. It is further envisionedthat cutting ring 620 is made of a flexible material (e.g.,polyethylene) to further facilitate assembly.

With reference to FIGS. 26 and 27, proximal surface 632 of tabs 630 isconfigured to engage lip 611 of groove 610 to help ensure engagementtherebetween. More particularly, in use, when knife 440 is advanced tocut tissue, knife 440 also penetrates severable portion 628, whichseparates outer ring 622 and inner ring 624 (see FIG. 27). As shown inFIG. 27 when compared to FIG. 26, distal advancement of knife 440 alsopushes cutting ring 620 distally within cavity 608. The engagementbetween outer ring 622 of cutting ring 620 and anvil head 600 helpsensure outer ring 622 is removed from the surgical site when anvil head600 is removed.

With reference to FIGS. 28-30, further details of anvil assembly 105 andits retention rod 108 are illustrated in accordance with embodiments ofthe present disclosure. As discussed above, anvil head 600 is pivotablyengaged with retention rod 108, e.g., to facilitate removal of anvilassembly 105 from within tissue. In use, tissue “T” is tied orpurse-string sutured to a distal portion 108 a of retention rod 108.Distal portion 108 a is defined as being disposed distally of a lip 109,which is configured to limit proximal travel of tissue “T,” and as beingthe portion of retention rod 108 that is configured to contact tissue“T.”

In the illustrated embodiment, distal portion 108 a of retention rod 108is tapered along its entire length. Further, distal portion 108 aincludes a continuous taper, which includes a concave portion 108 b anda convex portion 108 c. As shown, distal portion 108 a lacks a steppedconfiguration and lacks abrupt angle changes. It is envisioned that thistapered configuration of distal portion 108 a of retention rod 108 helpspurse-string sutured tissue “T” easily slide proximally when anvil head600 tilts and thus urges tissue “T” proximally (see FIG. 30).

With reference to FIGS. 31-34, retention rod 108 of anvil assembly 105is configured to selectively engage a trocar 700 extending distallybeyond cartridge assembly 110. More particularly, this embodimentillustrates a first retention rod 108′ that is configured to engage afirst trocar 700′ (FIG. 32), and a second retention rod 108″ that isconfigured to engage a second trocar 700″ (FIG. 32A). Here, however,first retention rod 108′ cannot properly engage second trocar 700″ (FIG.33), and second retention rod 108″ cannot properly engage first trocar700′ (FIG. 34). That is, engagement between first retention rod 108′ andfirst trocar 700′, and between second retention rod 108″ and secondtrocar 700″ would result in the two components securely engaging eachother such that longitudinal translation of the first component (e.g.,first retention rod 108′) in the opposite direction of the secondcomponent (e.g., first trocar 700′) would result in a correspondingamount of longitudinal translation of the second component. Conversely,an attempted engagement between first retention rod 108′ and secondtrocar 700″, or between second retention rod 108″ and first trocar 700′would result in the two components being free from secure engagementwith each other such that longitudinal translation of the firstcomponent (e.g., first retention rod 108′) in the opposite direction ofthe second component (e.g., second trocar 700″) would cause the firstcomponent to move away from the second component.

It is envisioned that each of first retention rod 108′ and first trocar700′ are configured for use with a particular configuration of staples.For instance, it is envisioned that first retention rod 108′ is part ofan anvil assembly 105 that includes two rows of staple-deforming pockets602, and that first trocar 700′ is part of/usable with a shell assembly100 including two rows of pusher elements 546 and a staple cartridge 150having two rows of staples “S.” Likewise, it is envisioned that secondretention rod 108″ is part of an anvil assembly 105 that includes threerows of staple-deforming pockets 602, and that second trocar 700″ ispart of/usable with a shell assembly 100 including three rows of pusherelements 546 and a staple cartridge 150 having three rows of staples“S.”

More particularly, first retention rod 108′ includes a recess 108′R thatis configured to engage a lip 700′L extending from first trocar 700′(FIG. 32). Similarly, second retention rod 108″ includes a recess 108″Rthat is configured to engage a lip 700″L extending from second trocar700″ (FIG. 32A). The geometry of retention rods 108′, 108″ and trocars700′, 700″ enable this mistake-proof engagement therebetween. Moreparticularly, and with reference to FIGS. 32 and 32A, it is envisionedand illustrated that first retention rod 108′ includes a larger diameterdr′ than a corresponding diameter dr″ of second retention rod 108″.Here, first trocar 700′ includes a larger diameter dt′ than acorresponding diameter dt″ of second trocar 700″. Additionally, it isenvisioned and illustrated that the distance between recess 108′R and aproximal lip 108′P of first retention rod 108′ is shorter than thedistance between recess 108″R and a proximal lip 108″P of secondretention rod 108″. Likewise, the illustrated embodiments show that thedistance between lip 700′L and a tip 700′T of first trocar 700′ isshorter than a corresponding distance between lip 700″L and a tip 700″Tof second trocar 700″.

With reference to FIGS. 33 and 34, recess 108′R of first retention rod108′ is not able to properly engage lip 700″L of second trocar 700″(FIG. 33), and recess 108″R of second retention rod 108″ is not able toproperly engage lip 700′L of first trocar 700′ (FIG. 34), e.g., due tothe various geometries discussed above. As discussed above, properengagement between a retention rod 108 and a trocar 700 is the secureengagement therebetween.

Additionally, it is envisioned that each of first trocar 700′ and secondtrocar 700″ includes an indicator 702 that is perceptible to a user ifthere is not proper engagement between a retention rod 108 and a trocar700 (e.g., if a user attempts to engage first retention rod 108′ withsecond trocar 700″, or vice versa). The present disclosure includesindicators 702 that provide visual (e.g., a colored band, letters,symbols, etc.), audio (e.g., beeps, clicks, etc.) and/or tactile (e.g.,vibration, etc.) information As illustrated, indicator 702 is notperceptible (e.g., visible) when there is proper engagement between aretention rod 108 and a trocar 700. Alternatively, it is envisioned thatindicator 702 is perceptible to a user if there is proper engagementbetween a retention rod 108 and a trocar 700, and indicator 702 is nonperceptible to a user if there is not proper engagement between aretention rod 108 and a trocar 700.

Referring now to FIGS. 35-39, details regarding the engagement betweendrive member 800 and pusher adapter 532 are shown in accordance with anembodiment of the present disclosure. During use of this embodiment ofcircular stapler 10, an initial actuation stroke is performed to firestaples “S” into tissue. Here, drive member 800 (or a portion thereof)is distally advanced into engagement with pusher adapter 532, andcontinued advancement of drive member 800 causes pusher adapter 532 tourge pusher member 540 distally to eject the staples “S” (as discussedabove). Next, drive member 800 and pusher adapter 532 are retractedproximally (while pusher member 540 remains in its advanced position).Then, in response to a second actuation stroke, for example, drivemember 800 and pusher adapter 532 are again advanced distally so thatpusher adapter 532 urges and/or engages knife carrier 420 distally tosever tissue. As can be appreciated, this embodiment differs fromembodiments described above, as here, independent actuation strokes arecompleted by the same drive member 800 completing two strokes (asopposed to the use of two separate drive members being used).

FIGS. 35-39 illustrate various features of the engagement between drivemember 800 and pusher adapter 532, which are configured to helpfacilitate engagement therebetween, and to help ensure engagementtherebetween during advancement and retraction of drive member 800. Moreparticularly, drive member 800 (e.g., an adapter nut) includes a recess802 (e.g., an annular recess) configured to engage tabs 810 on fingers820 on proximal portion 533 of pusher adapter 532. As drive member 800is distally translated and contacts pusher adapter 532, a distal surface804 of drive member 800 contacts tabs 810 and forces tabs 810 andfingers 820 radially inward (FIG. 37). Continued advancement of drivemember 800 with respect to pusher adapter 532 causes tabs 810 andfingers 820 to move radially outward, such that tabs 810 are withinrecess 802 (FIGS. 38 and 39).

In disclosed embodiments and with particular reference to FIGS. 36 and37, a distal wall 803 of recess 802 forms an angle α1 of between about70° and about 90° with respect to the longitudinal axis A-A. Inembodiments, angle α1 is between about 70° and about 80°, or betweenabout 75° and about 78°. Similarly, a distal wall 812 of tabs 810 formsan angle α2 of between about 70° and about 90° with respect to thelongitudinal axis A-A. In embodiments, angle α2 is between about 70° andabout 80°, or between about 75° and about 78°. It is envisioned that theangles formed by distal wall 803 of recess 802 and by distal wall 812 oftables 810 are equal, substantially equal, or differently from eachother.

Additionally, in disclosed embodiments, the height “h” of tabs 810 (andthe corresponding depth of the corresponding portion of recess 802) isbetween about 0.010 inches and about 0.020 inches (see FIG. 36). Inembodiments, height “h” is approximately equal to 0.015 inches.

It is further disclosed that pusher adapter 532 (or at least fingers 820thereof) is made from glass-filled polycarbonate. Here, it is envisionedthat the percentage of glass is between about 20% and about 40% (e.g.,about equal to 30%).

It is envisioned that the combination of the angles of distal walls 803and 812, the height “h” of tabs 810, and the material that pusheradapter 532 is made from all contribute to a secure engagement betweenpusher adapter 532 and drive member 800, and result in an optimum amountof force necessary to disengage pusher adapter 532 from drive member800.

With reference to FIGS. 40 and 41, the present disclosure also includesa communication chip assembly 900, which is configured to communicatevarious information to and from other portions of circular stapler 10.With particular reference to FIG. 40, communication chip assembly 900includes a case 910 housing a communication chip 902. Case 910 includesa tube portion 912 and a ring portion 914. With reference to FIG. 41,tube portion 912 of case 910 is configured to be press-fit into housing120 of shell assembly 100. Ring portion 914 is configured forsurrounding (or at least partially surrounding) inner cylindrical body124 of housing 120 (e.g., via a compression-fit arrangement).Additionally, case 910 includes a plurality of tabs 916 that areconfigured to engage respective slots/detents (not explicitly shown) inhousing 120 to help prevent rotation of communication chip assembly 900with respect to housing 120.

A proximal portion of communication chip 902 includes a plurality ofcontacts 904 for engaging contact pins of a portion (e.g., adaptor—notshown) of circular stapler 10. As can be appreciated, this engagementbetween contacts 904 and contact pins allows information to becommunicated from one portion of circular stapler 10 (e.g. handleassembly 20) to shell assembly 100. Further, communication chip 902 isspring-loaded via a biasing member 918 in a proximal direction (e.g., toallow for positional length tolerance of the contact pins in theadapter).

It is envisioned that communication chip 902 includes both read andwrite capability, and is particularly useful with a powered surgicalstapler. The read capability of communication chip 902 enablescommunication of various features of shell assembly 100 to handleassembly 20. For example, communication chip 902 can store and relayinformation relating to cartridge size, staple length, and clamp-updistance. Once this information is received by handle assembly 20, forexample, firing forces and firing stroke can be adjusted accordingly.

The write capability of communication chip 902 enables handle assembly20, for example, to encode a used (i.e., fired) cartridge assembly 110to prevent reuse or attempted firing of a staple-less cartridge assembly110. Further details of communication components (e.g., chips,transmitters, control modules, etc.) are disclosed in U.S. patentapplication Ser. No. 13/545,362, which was filed on Jul. 10, 2012, nowU.S. Pat. No. 8,506,557, the entire contents of which being incorporatedby reference herein.

The use of circular stapler 10 will now be described as it pertains tovarious embodiments of the present disclosure. In use, circular stapler10 is operated in a manner substantially similar to a traditionalcircular stapler. Once oriented such that the tissue to be stapled isreceived between cartridge assembly 110 and anvil assembly 105, andanvil assembly 105 is approximated towards cartridge assembly 110 viarotation of approximation knob 26, trigger 24 may be squeezed to causethe actuation of handle assembly 20. Actuation of handle assembly 20causes a first advancement of a drive assembly (e.g., 800) which engagesand causes the advancement of pusher assembly 530. During the first orstaple forming stroke, pusher assembly 530 is moved relative to housing120 and knife assembly 400, while knife assembly 400 remains stationaryrelative to housing 120. In this manner, during the first or stapleforming stroke of circular stapler 10 only the staple forming functionis performed. Accordingly, the force required for completion of thefirst stroke of circular stapler 10 does not include the force necessaryto also cut the tissue simultaneously therewith.

Upon completion of the first or staple forming stroke, trigger 24 isreleased to permit the retraction of the drive member and pusher adapter532 of pusher assembly 530. In various embodiments, pusher adapter 532is retracted to a position proximal of its initial position. Forexample, it is envisioned that pusher adapter 532 is retracted about0.25 inches farther proximally from its initial starting position. Inthis retracted position, notch 535 formed in the distal end of pusheradapter 532 is aligned with snap ring 180 thereby allowing snap ring 180to expand from the first or compressed condition to the second oruncompressed condition.

A subsequent squeezing or actuation of trigger 24 causes a secondadvancement of the drive member and pusher adapter 532. Advancement ofpusher adapter 532 causes engagement of ledge 536 of pusher adapter 532with snap ring 180. Since snap ring 180 remains engaged with knifecarrier 420 in this position, advancement of pusher adapter 532 alsocauses the advancement of knife assembly 420. Advancement of circularknife 440 of knife assembly 400 causes the cutting of tissue positionedbetween cartridge assembly 110 and anvil assembly 105. Because staples“S” were ejected and formed during the first stroke of circular stapler10, and pusher member 540 remained in the advanced position uponretraction of pusher adapter 532 following the first or staple formingstroke, the force required to complete the second or cutting stroke ofcircular stapler 10 is less then the force that would be necessary tocomplete both the staple ejecting/forming and tissue cutting procedure.It is envisioned that the force provided by the drive member during thesecond stroke would be sufficient to disengage any securing mechanismmaintaining knife assembly 400 relative to inner cylindrical housing 124of housing 120. Such securing mechanism may include protrusions (notshown) formed on the inner surface of knife carrier 420 and/or on theouter surface of inner cylindrical portion 124 of housing 120 configuredto be received within detents (not shown) formed on the other of theouter surface of inner cylindrical portion 124 and/or on the innersurface of knife carrier 420 such that knife assembly 400 is permittedto advance distally relative to housing 120.

Upon completion of the tissue cutting stroke, pusher adapter 532 isretracted proximally to one of the initial position or the retractedposition. As discussed above, pusher assembly 530 and knife assembly 400may be configured such that either or both of pusher assembly 530 andknife assembly 400 are retracted following the second or cutting strokeof circular stapler 10. Retraction of pusher adapter 532 to one of theinitial or retracted positions causes disengagement of pusher member 540from pusher adapter 532. In this manner, pusher member 540 and emptystaple cartridge 150 may be separated or unloaded from housing 120 andreplaced with a new pusher member 540 and/or staple cartridge 150.

Further details regarding the operation of circular stapler 10,including the operation of cartridge assembly 110, will now be describedas it pertains to various embodiments of the present disclosure. In theinitial condition, pusher assembly 530 is received between outer andinner cylindrical portions 122, 124 of housing 120. Knife assembly 400is received within longitudinal passage 531 of pusher adapter 532 andabout inner cylindrical portion 124 of housing 120. Staple cartridge 150is in operative engagement with a distal portion of housing 120 tooperably retain pusher assembly 530 and knife assembly 400 withinhousing 120. Snap ring 180 is in the first or radially compressedcondition and received within annular groove 463 formed on knife carrier420. Snap ring 180 is maintained in the radially compressed condition byan inner wall of pusher adapter 532. Notch 535 formed in the distal endof pusher adapter 532 is disposed distal of annular groove 463 and snapring 180. In this manner, pusher assembly 530 may be advanced distallywithout causing the advancement of knife assembly 400.

In the initial position, pusher assembly 530 is prevented frominadvertent distal advancement relative to housing 120 throughengagement of the plurality of paired detents 538 a, 538 b (FIG. 3)formed on distal portion 534 of pusher adapter 532 with openings 129formed in outer cylindrical portion 122 of housing 120.

During a first or staple forming stroke of circular stapler 10,following approximation of anvil assembly 105 with respect to cartridgeassembly 110 (e.g., via rotation of approximation knob 26), actuation oftrigger 24 relative to handle 22 causes advancement of a drive assembly(e.g., 800) which operably engages pusher adapter 532 to cause thedistal translation of pusher assembly 530. Distal translation of pusheradapter 532 advances pusher member 540 thereby causing pusher elements546 to be advanced into and/or through staple receiving pockets 152 ofstaple cartridge 150 and to eject staples “S” from staple cartridge 150.Although not explicitly shown, the ejection of staples “S” from staplecartridge 150 causes advancement of staples “S” into staple-deformingpockets 602 of anvil head 600. Forming of staples “S” secures the tissueretained between staple cartridge 150 and anvil assembly 105.

Upon completion of the stapling stroke, pusher adapter 532 is retractedproximally relative to housing 120. Pusher adapter 532 is sufficientlyretracted relative to knife carrier 420 and snap ring 180 such that snapring 180 is aligned with notch 535 formed in the distal end of pusheradapter 532. Alignment of notch 535 with snap ring 180 allows snap ring180 to move from the first or compressed condition to the uncompressedcondition, i.e., snap ring 180 is able to decompress or radially expand.

During the second or cutting stroke of circular stapler 10, a secondactuation of trigger 24 relative to handle 26 causes advancement of thedrive member (e.g., 800) which operably engages pusher adapter 532 tocause the distal translation of pusher adapter 532. Distal translationof pusher adapter 532 causes ledge 536, defined by notch 535 formed inthe distal end of pusher adapter 532, to engage an outer portion of snapring 180 while an inner portion of snap ring 180 remains engaged withknife carrier 420. In particular, step 142 a, formed within/adjacentgroove 463 of knife carrier 420, engages snap ring 180 and prevents snapring 180 from being radially compressed back into annular groove 463during the second advancement of pusher adapter 532 during the second ortissue cutting stroke of circular stapler 10. Accordingly, step 462 a ofknife carrier 420 maintains snap ring 180 in the second or expandedcondition such that snap ring 180 remains in contact with both pusheradapter 532 and knife carrier 420 to assure the simultaneous advancementof knife assembly 400 with the advancement of pusher adapter 532.

Continued advancement of pusher adapter 532 causes knife 440 to bereceived through longitudinal opening 151 of staple cartridge 150,thereby severing the tissue retained between staple cartridge 150 andanvil assembly 105, and thereby penetrating severable portion 628 ofcutting ring 620. It is envisioned that pusher assembly 530 and knifeassembly 400 may be configured such that retraction of the driveassembly causes the retraction of pusher adapter 532 and knife carrier420 (see FIGS. 11-21, for example).

In addition to the reduced force requirements provided by the two strokeoperation of circular stapler 10, the independent or decoupled stapleforming and tissue cutting function of circular stapler 10 also permitsthe varying of the staple crimp height relative to the knife traveldistance, the varying of the staple travel speed relative to the knifetravel speed, and/or the addition of a dwell time between stapleformation and tissue cutting. This configuration allows a clinician tooptimize staple crimp heights to given conditions, such as, tissuethickness, tissue compliance and clamping force. This configuration mayalso allow for the monitoring of staple forming and knife cuttingforces, to alert the clinician in case an abnormal force is detected.This configuration further allows force and other data to be monitoredand used for data collection and research, which when analyzed, may leadto further optimization of operational parameters, such as staple crimpheight, and dwell and travel speed. By independently controlling andoptimizing these various parameters, improved hemostasis and anastomonicjoint strength may result across a much broader range of tissuethicknesses, thereby allowing a clinician to have improved andcustomized control over the results. Further still, when the staplingand cutting functions are performed at the same time, the tissue beingstapled may be displaced by the knife, thereby causing the staple legsto deflect and misalign with their intended anvil pockets, resulting inpoor staple formation and possible leakage.

It will be understood that various modifications may be made to theembodiments disclosed herein. For example, circular stapler 10 mayinclude a mechanism for changing cartridge assembly 110 from two strokeoperation to a single stroke operation. Therefore, the above descriptionshould not be construed as limiting, but merely as exemplifications ofparticular embodiments. Those skilled in the art will envision othermodifications within the scope and spirit of the claims appended hereto.

1. (canceled)
 2. A surgical kit, comprising: a first trocar configuredfor use with a first cartridge; a second trocar configured for use witha second cartridge; a first anvil assembly including a first retentionrod configured to selectively engage the first trocar; and a secondanvil assembly including a second retention rod configured toselectively engage the second trocar, wherein at least one of the firsttrocar or the second retention rod includes structure configured tophysically prevent proper engagement therebetween.
 3. The surgical kitaccording to claim 2, wherein at least one of the second trocar or thefirst retention rod includes structure configured to physically preventproper engagement therebetween.
 4. The surgical kit according to claim2, further including a first cartridge configured to house a pluralityof staples in a first pattern.
 5. The surgical kit according to claim 4,further including a second cartridge configured to house a plurality ofstaples in a second pattern.
 6. The surgical kit according to claim 5,wherein the first anvil assembly includes a plurality of stapledeforming pockets arranged in the first pattern.
 7. The surgical kitaccording to claim 6, wherein the second anvil assembly includes aplurality of staple deforming pockets arranged in the second pattern. 8.The surgical kit according to claim 2, wherein the first trocar includesat least one indicator that is perceptible by a user when the firsttrocar is improperly engaged with the second retention rod.
 9. Thesurgical kit according to claim 8, wherein the at least one indicator isnot perceptible by a user when the first trocar is properly engaged withthe first retention rod.
 10. The surgical kit according to claim 2,wherein the first retention rod includes a recess that is configured toengage a lip of the first trocar, and wherein the second retention rodincludes a recess that is configured to engage a lip of the secondtrocar.
 11. The surgical kit according to claim 2, wherein the firstretention rod includes a larger diameter than a corresponding diameterof the second retention rod.
 12. A shell assembly kit for use with acircular stapler, comprising: a first staple cartridge configured tohouse two rows of staples; a first trocar disposed in mechanicalcooperation with the first staple cartridge; a second staple cartridgeconfigured to house three rows of staples; a second trocar disposed inmechanical cooperation with the second staple cartridge; a first anvilassembly including two rows of staple deforming pockets, and including afirst retention rod configured to selectively engage the first trocar;and a second anvil assembly including three rows of staple deformingpockets, and including a second retention rod configured to selectivelyengage the second trocar, wherein at least one of the first trocar orthe second retention rod includes structure configured to physicallyprevent proper engagement therebetween.
 13. The shell assembly kitaccording to claim 12, wherein at least one of the second trocar or thefirst retention rod includes structure configured to physically preventproper engagement therebetween.
 14. The shell assembly kit according toclaim 12, wherein the first trocar includes at least one indicator thatis perceptible by a user when the first trocar is improperly engagedwith the second retention rod.
 15. The shell assembly kit according toclaim 14, wherein the at least one indicator is not perceptible by auser when the first trocar is properly engaged with the first retentionrod.
 16. The shell assembly kit according to claim 12, wherein the firstretention rod includes a recess that is configured to engage a lip ofthe first trocar.
 17. The shell assembly kit according to claim 16,wherein the second retention rod includes a recess that is configured toengage a lip of the second trocar.
 18. The shell assembly kit accordingto claim 12, wherein the first retention rod includes a larger diameterthan a corresponding diameter of the second retention rod.
 19. The shellassembly kit according to claim 12, wherein each of the first retentionrod and the second retention rod includes a recess and a proximal lip,and wherein a distance between the recess and the proximal lip of thefirst retention rod is less than a distance between the recess and theproximal lip of the second retention rod.
 20. The shell assembly kitaccording to claim 12, wherein a tissue-contacting portion of the firstretention rod is tapered along its entire length.
 21. The shell assemblykit according to claim 20, wherein the first anvil assembly includes ananvil head that is tiltable relative to the first retention rod.